This invention relates to a scroll compressor having a floating seal which has a protection device which is actuated upon reverse rotation.
Scroll compressors are becoming increasingly popular for refrigerant compression applications. In a scroll compressor a first scroll member has a base and a generally spiral wrap extending from the base.
A second scroll member also has a base and a generally spiral wrap extending from its base. The wraps of the first and second scroll member interfit to define compression chambers. The second scroll member is caused to orbit relative to the first scroll member, and as the wraps orbit relative to each other, a refrigerant to be compressed is entrapped and moved toward a discharge port.
As the refrigerant is compressed, a force is created tending to separate the first and second scroll member. One technique utilized to address this separating force is a back pressure chamber. A back pressure chamber is defined by tapping a compressed fluid to a chamber defined by seals behind one of the first or second scroll members. The fluid in the chamber creates a force in opposition to the separating force. In one known type of scroll compressor, the first scroll member, known as the non-orbiting scroll, is axially moveable relative to the second scroll member. A seal is placed in the base of the non-orbiting scroll and defines the back pressure chamber. This seal also separates an inlet zone from a discharge pressure zone.
During normal operation the seal is biased into contact with another component in the scroll compressor. Typically, the seal is biased against a separator plate which defines a discharge pressure chamber above the non-orbiting scroll. The seal is moveable away from the separator plate wall to allow the discharge and suction pressure zones to communicate.
Scroll compressors are sometimes prone to operation in a reverse direction. When the scroll compressor is operated in a reverse direction, the refrigerant is drawn through the discharge port, into the compression chambers, and then outwardly through the suction port. Operation in reverse rotation is undesirable, and potentially detrimental to the scroll compressor.
In the prior art mentioned above, operation in the reverse rotation will typically draw the seal away from the separator plate wall, allowing the discharge and suction pressure zones to communicate. This is true since the fluid which is tapped to the back pressure chamber will be at a very low pressure during reverse rotation. The seal will thus be drawn away from the plate, allowing communication between the discharge and suction pressure zone. This is somewhat undesirable, as oil is allowed to enter the discharge port from the suction pressure zone. The oil is then pumped through the scrolls and out of the compressor through a suction tube. This can lead to a loss of oil within the scroll compressor.
It would be desirable to have a scroll compressor seal which is structured to prevent the communication of the suction and discharge pressure zones during reverse rotation.